Significant advances in industrial process control technology have vastly improved all aspects of factory and plant operation. Before the introduction of today's modem industrial process control systems, industrial processes were operated/controlled by humans and rudimentary mechanical controls. As a consequence, the complexity and degree of control over a process was limited by the speed with which one or more people could ascertain a present status of various process state variables, compare the current status to a desired operating level, calculate a corrective action (if needed), and implement a change to a control point to affect a change to a state variable.
Improvements to process control technology have enabled vastly larger and more complex industrial processes to be controlled via programmed control processors. Control processors execute control programs that read process status variables and execute control algorithms based upon the status variable data and desired set point information to render output values for the control points in industrial processes. Such control processors and programs support a substantially self-running industrial process (once set points are established).
Notwithstanding the ability of industrial processes to operate under the control of programmed process controllers at previously established set points without intervention, supervisory control and monitoring of control processors and their associated processes are desirable. Such oversight is provided by both humans and higher-level control programs at an application/human interface layer of a multilevel process control network. Such oversight is generally desired to verify proper execution of the controlled process under the lower-level process controllers and to configure the set points of the controlled process.
Data access servers facilitate placing process control data within reach of a variety of higher-level monitoring/control client applications. During the course of operation, process controllers generate status and control information concerning associated processes. The controllers' process status and control information is stored within process control databases and/or distributed to a number of locations within the process control network. Other process information is generated/stored within field devices (e.g., intelligent transmitters) having digital data communication capabilities. The process information is retrieved from the databases and field devices by data servers for further processing/use by the process control system. For example, the data access servers provide the retrieved information to a variety of client applications providing high-level control and monitoring (both human and computerized) services.
In systems containing data access servers, the high-level control and monitoring applications rely upon the proper operation of the data access servers to provide the data upon which such applications rely for decision-making. Such information includes real-time process variable values, alarms, etc. If a data access server is providing inaccurate or outdated information, then the decision-making process of the high-level control and monitoring applications becomes corrupt. It is therefore important to quickly identify and address malfunctioning data sources such as the data access servers and/or the lower-level devices and control processors that feed process control data to the data access servers.
Many data access servers operate in complex process control computing environments in a time-critical manner. In very large systems, with hundreds, or even thousands, of data access servers spread across hundreds or thousands of computers in many buildings, the cost of tuning the operation of running data access servers and the devices from which they receive their data grows exponentially with the number of such servers. The delay in completing tuning operations also increases. Such delays are costly to manufacturers. Therefore, manufacturers generally seek to minimize the delays encountered when tuning the operation of a data access server and its associated process control devices.
Moreover, it is important to quickly identify and remedy operation faults in an industrial/manufacturing process managed by a process control system. A data access server that is malfunctioning or unable to function because a physical device connected to it is malfunctioning can result in significant downtime for a manufacturing process. In many applications, if the information or control pathway provided by a data access server is unavailable, whole production lines can be brought to a standstill.